U.N. chief Ban Ki-moon has appointed British lawmaker Stephen O'Brien as the U.N.'s top humanitarian aid official to lead global relief efforts at a time of worsening conflicts, the U.N. announced Monday.

O'Brien will replace Valerie Amos who served as under-secretary for humanitarian affairs and emergency relief for the past four years, earning high praise for her commitment in one of the U.N.'s most demanding posts.

The United States has begun to deploy 3,000 troops on a three-month exercise to reassure Russia's nervous neighbors in the Baltic, military officials said Monday.

Operation Atlantic Resolve will see major NATO forces working alongside their allies in Latvia, Lithuania and Estonia -- former Soviet republics now members of the Western alliance.

The White House on Monday denounced efforts by Republican lawmakers to "throw sand in the gears" of sensitive talks over Iran's nuclear program as "partisan."

Forty-seven Republicans, including Senate leaders and several potential 2016 presidential candidates, wrote an open letter to Iran's leader, warning any deal with President Barack Obama might not be honored in future.

Turkey's powerful former intelligence chief announced Monday he is dropping a bid to run for parliament in the wake of criticism from President Recep Tayyip Erdogan over his decision to resign and seek elected office.

"As of today, I deem it necessary to withdraw my application to run... in the general elections," Fidan said in a statement carried by the state-run Anatolia news agency.

Ukraine accused pro-Russian separatists Monday of using mortars and a tank to fire on government positions near the eastern port of Mariupol in clashes that lasted several hours, violating a nearly month old ceasefire.

The militants had fired on Ukraine's positions and were attempting to "force our contingents from Shyrokyne," a village about 10 kilometers east of Mariupol on the Azov Sea coast, the headquarters of the army's operations in the east said in a Facebook post.

Venezuela recalled its envoy to Washington for consultations Monday, after U.S. President Barack Obama ordered new sanctions against senior Venezuelan officials.

"We call Maximilien Arvelaiz, charge d'affaires in the United States, for immediate consultations," Foreign Minister Delcy Rodriguez wrote on Twitter.

Russia has vastly enhanced its military capabilities in Crimea since annexing the peninsula, turning it into a "power projection platform," a senior NATO general was reported Monday as saying.

"What we've seen is easy to describe as the militarization of Crimea," the alliance's top commander for Europe, General Philip Breedlove, said in an interview with Ukrainian channel 1+1.

Russian President Vladimir Putin on Monday awarded a medal of honor to the chief suspect in the murder of former Russian security agent Alexander Litvinenko for "services to the fatherland".

The Kremlin released an honors list including Andrei Lugovoi, a lawmaker in a nationalist party who is wanted by Britain over the poisoning of Litvinenko in 2006.

The United States on Monday delivered more than 100 pieces of military equipment to vulnerable NATO-allied Baltic states in a move designed to provide them with the ability to deter potential Russian threats.

The deliveries are intended to "demonstrate resolve to President (Vladimir) Putin and Russia that collectively we can come together," U.S. Major General John R. O'Connor told Agence France Presse as he oversaw the delivery of the equipment in the port of Riga. 

Four people have been detained over their connections to one of the jihadists who carried out the Paris attacks in January, a judicial source said on Monday.

The four are said to be friends with Amedy Coulibaly, who killed four people at a Jewish supermarket and a policewoman during the January 7-9 attacks.