By Alexander Cornwell and Maya Gebeily

TEL AVIV/BEIRUT, March 24 (Reuters) - Israel's military will occupy southern Lebanon up to the Litani River, defence minister Israel Katz said on Tuesday, the first time Israel has clearly spelled out its intent to seize swathes of territory that make up nearly a tenth of Lebanon.

Katz has previously threatened Lebanon's government it would lose territory if it did not disarm Hezbollah, the militant group backed by Tehran that drew Lebanon into the U.S.-Israeli war on Iran when it fired into Israel on March 2.

He is, according to President Donald Trump, a "top person" in the Iranian system who is "most respected" and is in an unenviable position.

But who is the senior figure talking with the United States on the future of Iran after over three weeks of the Israeli-US war against the Islamic republic?

The individual, said Trump, is not supreme leader Mojtaba Khamenei who succeeded his father, Ali Khamenei, after the killing of the ex-number one at the start of the war on February 28.

At an archaeological site in southern Lebanon's Tyre, small signs bearing a blue and white emblem provide a symbolic shield, meant to protect the ancient ruins from bombardment.

One of the oldest cities on the Mediterranean coast, Tyre is located around 20 kilometres (12 miles) from the Israeli border, and has been the target of several strikes since Lebanon was drawn into the Middle East war by Hezbollah's March 2 rocket attack on Israel.

German President Frank-Walter Steinmeier spoke on Tuesday of a "deep rift" with traditional ally the United States and said the US-Israeli war on Iran was a "breach of international law".

In unusually strong comments, the German head of state said that just as there was no going back from Russia's 2022 full-scale invasion of Ukraine, "there will be no going back to before January 20, 2025", when US President Donald Trump entered the White House for a second time.

PARIS, March 24 (Reuters) - France's army chief said on Tuesday that the United States had become an unpredictable ally that was impacting France's interests and security.

"We were surprised by an American ally, who remains an ally, but who is becoming increasingly unpredictable and doesn't even bother to inform us when they decide to launch military operations," Fabien Mandon told a security and defence forum in Paris.

"It has an impact on our security and it has an impact on our interests."

By Andreas Rinke and Miranda Murray

BERLIN, March 24 (Reuters) - The Iran war is a "disastrous mistake" that breaches international law, Germany's president said on Tuesday in an unusually blunt rebuke of U.S. President Donald Trump's foreign policy, which he said marked a rupture for German ties with its biggest post-war ally.

In a scathing verbal attack, Frank-Walter Steinmeier, whose largely ceremonial role allows him to speak more freely than politicians, took a far more critical line than Chancellor Friedrich Merz, who has skirted questions on the war's legality.

March 24 (Reuters) - Russia would view any spillover of the Iran conflict into the Caspian Sea "extremely negatively", Kremlin spokesman Dmitry Peskov said on Tuesday.

Israel said last week its military had carried out strikes on the Iranian navy in the Caspian, hitting dozens of targets including missile boats. A military spokesperson said Israel had managed to take out Iran's naval capabilities there.

Russia and Iran, which signed a strategic partnership treaty last year, both border the Caspian Sea.

BERLIN, March 24 (Reuters) - Germany's foreign minister said on Tuesday that he believed U.S. President Donald Trump's announcement about talks with Iran could mark a turning point in the nearly month-long conflict.

"Something is happening, and that's a good thing in this time when there have been more risks of escalation than possibilities of bringing this conflict under control," Foreign Minister Johann Wadephul told broadcaster MDR.

MOSCOW, March 24 (Reuters) - The Kremlin on Tuesday, when asked about a Reuters report that Russia was postponing a plan to boost long-term fiscal reserves, said that the issues were being worked out and that they were being discussed at President Vladimir Putin's meetings on the economy.

Reuters' sources said on March 23 that the government would now postpone a plan to boost long-term fiscal reserves due to the oil price spike triggered by the Iran war.

The UN Human Rights Council will hold a rare urgent debate on Wednesday on Iran's strikes on countries across the Gulf region and their impact on civilians.

The session, approved on Tuesday, was requested by Bahrain on behalf of the six Gulf Cooperation Council (GCC) countries and Jordan -- to the infuriation of Tehran, which branded them "detached from reality".