In Tehran, witnesses heard the blast. Iranian state television later reported on the explosion, without offering a cause.Sirens sounded across Israel at the same time.The Israeli military said that it had issued a proactive alert to prepare the public for the possibility of missiles being launched toward the state of Israel.

Israel launched a daylight attack Saturday on Iran's capital, with a cloud of smoke rising from the city's downtown, the Associated Press reported.

It wasn't immediately clear what the target was. But the attack comes as the United States has assembled a vast fleet of fighter jets and warships in the region to try to pressure Iran into a deal over its nuclear program.

Israeli Defense Minister Israel Katz described the attack as being done "to remove threats." He did not immediately elaborate.

In Tehran, witnesses heard the blast. Iranian state television later reported on the explosion, without offering a cause.

Sirens sounded across Israel at the same time. The Israeli military said that it had issued a "proactive alert to prepare the public for the possibility of missiles being launched toward the state of Israel."

The U.S. military declined to immediately comment on the attack.

President Donald Trump warned earlier in February that " really bad things " would happen unless Tehran agreed to a deal over the future of its nuclear program. The attack, which comes after a significant build up of military assets in the oil-rich Middle East region.

The U.S. and Iran had held a third round of talks in Switzerland on Thursday to try to resolve a standoff.

Ahead of the discussions, U.S. Secretary of State Marco Rubio said Iran's reluctance to talk about its ballistic missile development program, alongside its nuclear program, was a "big, big problem." Iran had said it was willing to compromise when it came to its nuclear program, but had repeatedly said Tehran's missile program had never been part of the talks' agenda.

There were earlier signs that Washington was losing its patience with Iran after the White House said, after previous talks, that Iran was not addressing its core demands.

Earlier in February, Iran reportedly said in a letter to United Nations Secretary-General Antonio Guterres that Tehran would respond "decisively" if subjected to military aggression.

Energy market participants have been closely monitoring the escalating geopolitical tensions, with oil prices climbing to six-month highs after Trump's amid concerns of a possible supply shock.

Iran, a founding member of OPEC, is a major oil producer and sits at the heart of the strategically vital Strait of Hormuz, through which about 20% of the world's oil passes.

Last June, the U.S. launched strikes on three Iranian nuclear facilities, causing what intelligence suggested was severe damage to Tehran's nuclear program. Iran responded by launching a retaliatory strike on an American air base in Qatar, reportedly causing minor damage but inflicting no casualties.

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在德黑兰，目击者听到了爆炸声。伊朗国家电视台随后报道了这起爆炸事件，但未说明原因。以色列各地在同一时间拉响了警报。以色列军方表示，已发布“主动预警”，提醒公众为导弹可能袭击以色列做好准备。

据美联社报道，以色列于周六白天对伊朗首都发动袭击，市中心上空升起滚滚浓烟。

袭击目标尚未明确。但此次攻击发生时，美国已在相关区域集结大批战机和军舰，试图迫使伊朗就其核计划达成协议。

以色列国防部长伊斯雷尔·卡茨将此次袭击描述为"旨在消除威胁"的行动，但未立即作出详细说明。

在德黑兰，目击者听到了爆炸声。伊朗国家电视台随后报道了这起爆炸事件，但未说明原因。

警报声同时在以色列各地响起。以色列军方表示，已发布“主动预警，提醒公众做好导弹可能袭击以色列的准备”。

美国军方拒绝立即对这起袭击事件发表评论。

唐纳德·特朗普总统曾在2月初警告称，除非德黑兰就其核计划的未来达成协议，否则将发生"非常糟糕的事情"。此次袭击发生前，石油资源丰富的中东地区已出现大规模的军事力量集结。

美国和伊朗于周四在瑞士举行了第三轮会谈，试图化解僵局。

在会谈前夕，美国国务卿马可·卢比奥表示，伊朗不愿讨论其弹道导弹发展计划与核计划并行的问题，称这是一个"极其严重的问题"。伊朗曾表示愿意在核计划问题上作出妥协，但多次强调德黑兰的导弹计划从未被列入谈判议程。

早前已有迹象表明，华盛顿方面对伊朗正失去耐心。此前白宫在几轮会谈后表示，伊朗并未满足其核心要求。

据报道，伊朗于2月初致函联合国秘书长安东尼奥·古特雷斯，称德黑兰若遭受军事侵略将予以"果断"回应。

能源市场参与者正密切关注不断升级的地缘政治紧张局势。在特朗普相关事件引发对潜在供应冲击的担忧后，油价已攀升至六个月高位。

伊朗是石油输出国组织（OPEC）的创始成员国之一，也是重要的石油生产国，其地理位置处于战略要地霍尔木兹海峡的核心区域，全球约20%的石油运输需经此通道。

去年6月，美国对伊朗三处核设施发动袭击，情报显示此举对德黑兰的核计划造成严重破坏。伊朗随即对卡塔尔一处美军空军基地实施报复性打击，据报道仅造成轻微损失，未导致人员伤亡。

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