If Russia can't reach a ceasefire agreement with Ukraine within 10 days, secondary sanctions will follow, President Trump said.

The United Kingdom set a September deadline for Israel to agree to a Gaza ceasefire or face the U.K.'s recognition of a Palestinian state.

The Kremlin is yet to officially comment on the new deadline. But Dmitry Medvedev -- the former Russian president and prime minister now serving as the deputy chairman of the country's Security Council -- framed Trump's challenge as a dangerous escalation.

The Kremlin said on Tuesday that it had "taken note" of a statement by U.S. President Donald Trump that he was shortening his deadline for Moscow to sign up to a ceasefire in Ukraine or face sanctions.

The U.S. has withdrawn from Doha ceasefire talks after Hamas' response showed a "lack of desire" for an agreement. Israel also pulled negotiators amid escalating demands.

Israeli Prime Minister Benjamin Netanyahu is considering a plan to annex territories in Gaza, two sources familiar with the matter told ABC News.

Hayya, said on Sunday ceasefire negotiations with Israel were "meaningless under continued blockade and starvation".