The coming week could bring an important moment inthe war between Russia and Ukraine, as U.S.President Donald Trump's deadline for the Kremlin to reach a peace deal approaches — or it could simply melt away. U.S. President Donald Trump's special envoySteve Witkoffwas expected in Moscow in the middle of this week, just beforeTrump's Friday deadlinefor the Kremlin to stop the killing or facepotentially severe economic penaltiesfrom Washington. Previous Trump promises, threats and cajoling havefailed to yield results., and the stubborn diplomatic stalemate will be hard to clear away. Meanwhile, Ukraine is losing more territory on the front line, although there is no sign of a looming collapse of its defenses. Trump envoy is expected at the Kremlin Witkoff was expected to land in the Russian capital on Wednesday or Thursday, according to Trump, following histrip to Israel and Gaza. "They would like to see (Witkoff)," Trump said Sunday of the Russians. "They've asked that he meet so we'll see what happens." Trump, exasperated that Russian President Vladimir Putin hasn't heeded his calls to stop bombing Ukrainian cities, a week agomoved up his ultimatumto impose additional sanctions on Russia as well as introduce secondary tariffs targeting countries that buy Russian oil, including China and India. Kremlin spokesman Dmitry Peskov said Monday that officials are happy to meet with Trump's envoy. "We are always glad to see Mr. Witkoff in Moscow," he said. "We consider (talks with Witkoff) important, substantive and very useful." Trump is not sure sanctions will work Trump said Sunday that Russia has proved to be "pretty good at avoiding sanctions." "They're wily characters," he said of the Russians. The Kremlin has insisted that international sanctions imposed since its February 2022 invasion of its neighbor have had a limited impact. Ukraine insists the sanctions are taking their toll on Moscow's war machine and wants Western allies to ramp them up. Ukrainian President Volodymyr Zelenskyy on Monday urged the United States, Europe and other nations to impose stronger secondary sanctions on Moscow's energy, trade and banking sectors. Trump's comments appeared to signal he doesn't have much hope that sanctions will force Putin's hand. The secondary sanctions also complicate Washington's relations with China and India, who stand accused of helping finance Russia's war effort bybuying its oil. Since taking office in January, Trump has found thatstopping the war is harderthan he perhaps imagined. Senior American officials have warned that the U.S. could walk away from the conflict if peace efforts make no progress. Putin shows no signs of making concessions The diplomatic atmosphere has become more heated as Trump's deadline approaches. Putin announced last Friday that Russia'snew hypersonic missile, the Oreshnik, has entered service. The Russian leader has hailed its capabilities, saying its multiple warheads that plunge to a target at speeds of up to Mach 10 cannot be intercepted. They are so powerful, he said, that the use of several of them in one conventional strike could be as devastating as a nuclear attack. Also, one of Putin's top lieutenants warned that the Ukraine war could nudge Russia and the U.S. into armed conflict. Trump responded to what he called the "highly provocative statements" by former Russian president Dmitry Medvedev by ordering therepositioning of two U.S. nuclear submarines. Putin has repeated the same message throughout the war: He willonly accept a settlement on his termsand will keep fighting until they're met. The war is killing thousands of troops and civilians Russia's relentless pounding of urban areas behind the front line have killed more than 12,000 Ukrainian civilians, according to the United Nations. It haspushed on with that tacticdespiteTrump's public calls for it to stopover the past three months. On the 1,000-kilometer (620-mile) front line, Russia's bigger army has made slow and costly progress. It is carrying outa sustained operationto take the eastern city of Pokrovsk, a key logistical hub whose fall could open the way for a deeper drive into Ukraine. Ukraine has developed technology that has allowed it to launch long-range drone attacks deep inside Russia. In itslatest strikeit hit an oil depot near Russia's Black Sea resort of Sochi, starting a major fire. ___ Follow AP's coverage of the war in Ukraine athttps://apnews.com/hub/russia-ukraine