BANDAR SERI BEGAWAN, Jan 14 (Reuters) - Brunei's ruler Sultan Hassanal Bolkiah will undergo knee replacement surgery this weekend, with a recovery period expected to last between two to three months, his office said.

The 79-year-old sultan, one of the world's longest-reigning monarchs, will be limiting his presence at national and official ceremonies during the recovery process for rest and physiotherapy sessions, the office said in a statement on Tuesday.

President Donald Trump said Tuesday that the United States would react strongly if authorities in Iran started hanging people in their crackdown on a popular uprising against the government.

"We will take very strong action if they do such a thing," he told CBS News in an interview, when asked about hangings potentially beginning on Wednesday.

"When they start killing thousands of people -- and now you're telling me about hanging. We'll see how that's going to work out for them," Trump said in a video clip released online.

Jan 13 (Reuters) - President Donald Trump said on Tuesday the United States would take "very strong action" if the Iranian government starts hanging protesters, but did not elaborate on what those actions would be.

"I haven't heard about the hanging. If they hang them, you're going to see some things... We will take very strong action if they do such a thing," Trump told CBS News in an interview.

(Reporting by Bhargav Acharya in Toronto;)

By Elwely Elwelly and Bo Erickson

DUBAI/DETROIT, Jan 13 (Reuters) - U.S. President Donald Trump urged Iranians on Tuesday to keep protesting and said help was on the way, without giving details, as Iran's clerical establishment pressed its crackdown against the biggest demonstrations in years.

"Iranian Patriots, KEEP PROTESTING - TAKE OVER YOUR INSTITUTIONS!!!... HELP IS ON ITS WAY," Trump said in a post on Truth Social, adding he had canceled all meetings with Iranian officials until the "senseless killing" of protesters stopped.

By Michelle Nichols

UNITED NATIONS, Jan 13 (Reuters) - U.N. Secretary-General Antonio Guterres has warned Israel in a letter that he could refer the country to the International Court of Justice if it does not repeal laws targeting U.N. Palestinian refugee agency UNRWA and return seized assets and property.

WASHINGTON, Jan 13 (Reuters) - White House envoy Steve Witkoff over the weekend met with Reza Pahlavi, the exiled son of Iran's last shah and a prominent voice in the fragmented opposition, to discuss the protests roiling that country, Axios reported on Tuesday, citing an unidentified senior U.S. official.

(Reporting by Susan Heavey; Editing by Doina Chiacu)

The United States on Tuesday designated the Muslim Brotherhood branches in Egypt, Lebanon and Jordan as terrorist organizations, fulfilling a long demand of Arab allies and US conservatives.

Founded in 1928 in Egypt, the pan-Islamist movement once spread across the Muslim world, but it has been in retreat as it comes under concerted pressure from major Arab powers.

Jan 13 (Reuters) - The United States on Tuesday designated the Egyptian, Lebanese and Jordanian branches of the Muslim Brotherhood as global terrorists, citing in part what it called their support for Palestinian militant group Hamas.

The move, which Washington formally set in motion last November, will bring sanctions against one of the Arab world's oldest and most influential Islamist movements.

Rubina was a budding fashion designer inspired by Iran's multi-ethnic population. Rebin was an up-and-coming teen footballer. Mehdi was a champion bodybuilder who also won weightlifting titles. Erfan had just turned 18.

All four, from various regions and backgrounds, were according to rights groups victims of the Iranian government's crackdown on protests, gunned down by security forces in their prime.

MOSCOW, Jan 13 (Reuters) - Russia on Tuesday condemned what it described as "subversive external interference" in Iran's internal politics and said U.S. threats of new military strikes against the country were "categorically unacceptable."

"Those who plan to use externally inspired unrest as a pretext for repeating the aggression against Iran committed in June 2025 must be aware of the disastrous consequences of such actions for the situation in the Middle East and global international security," the Russian Foreign Ministry said in a statement.