Iran said Turkey's criticism of its foreign policy risked worsening ties between the neighboring countries, after Islamist rebels allied with Ankara ousted Syria's Bashar al-Assad.

In an interview with Al Jazeera in February, Turkish Foreign Minister Hakan Fidan said Iran risked plunging the Middle East into "disorder".

The chief of the European Union's executive on Tuesday proposed an 800 billion euro ($841 billion) plan to beef up defenses of EU nations to lessen the impact of potential U.S. disengagement and provide Ukraine with military muscle to negotiate with Russia following the freeze of U.S. aid to the embattled nation.

European Commission President Ursula von der Leyen said the massive "REARM Europe" package will be put to the 27 EU leaders who will meet in Brussels on Thursday in an emergency meeting following a week of increasing political uncertainty from Washington, where President Donald Trump questioned both his alliance to the continent and the defense of Ukraine.

The Kremlin said on Tuesday that the lifting of U.S. economic sanctions on Russia was a prerequisite for normalizing ties between the two countries.

"Of course, if we're talking about normalizing bilateral relations, these relations must be free of the negative burden of sanctions," Kremlin spokesman Dmitry Peskov told a daily press briefing.

Russia said on Tuesday the suspension of U.S. aid to Ukraine following a public clash between their leaders, Donald Trump and Volodymyr Zelensky, was the best contribution to ending the Russia-Ukraine war.

"If the United States stops (military supplies), this would probably be the best contribution to peace," Kremlin spokesman Dmitry Peskov said, adding that it was a "solution which could really push the Kyiv regime to a peace process".

A former Iranian foreign minister who was key to the country's 2015 nuclear deal with world powers reportedly tendered his resignation on Monday from the government of reformist President Masoud Pezeshkian, caving in to pressure from hard-liners.

The resignation of Mohammad Javad Zarif signaled Tehran's rapid retreat from its outreach to the West as U.S. President Donald Trump intensifies sanctions on the country.

British Prime Minister Keir Starmer rallied his European counterparts Sunday to shore up their borders and throw their full weight behind Ukraine as he announced outlines of a plan to end Russia's war.

"Every nation must contribute to that in the best way that it can, bringing different capabilities and support to the table, but all taking responsibility to act, all stepping up their own share of the burden," he said.

Canadian Prime Minister Justin Trudeau will meet with King Charles III, the country's head of state, on Monday where he will discuss U.S. President Donald Trump's threats to make Canada the 51st state.

The king has come under criticism in Canada for being silent about Trump's threats to annex Canada.

The Kremlin on Monday described last week's angry exchange between Ukrainian President Volodymyr Zelensky and U.S. President Donald Trump at the Oval Office as "unprecedented".

"Quite an unprecedented event," Kremlin spokesman Dmitry Peskov said of the meeting in comments to journalists, adding that Zelensky "demonstrated a complete lack of diplomatic abilities. To put it mildly".

It was supposed to cap a week of whirlwind diplomacy advancing the prospect of peace in Ukraine.

But a summit of European leaders on Sunday has been overshadowed by the extraordinary scolding by U.S. President Donald Trump of Ukrainian President Volodymyr Zelenskyy at the White House on Friday for being ungrateful for U.S. support. The London meeting has now taken on greater importance in defending the war-torn ally and shoring up the continent's defenses.

European leaders threw their support behind Ukrainian President Volodymyr Zelensky after his spat with Donald Trump sent shockwaves across the world, casting doubts over efforts to end the Russia-Ukraine war.

The U.S. president openly berated Zelensky on Friday for not being "thankful", and later accused the Ukrainian leader of "not being ready for peace" and having "disrespected" the United States in the "cherished Oval Office".