Investments are captured in the current account (which includes the trade balance, factor payments and transfer payments plus a fudge factor for illegal and unaccountable capital flows). The current account deficit, not the trade deficit, is the more important and worrying statistic.
The trade deficit shows that the US is importing more than it exports, but the current account deficit shows that the US is spending more than it earns. The problem with a growing current account deficit is that an increasing proportion of US income (GDP) is required for factor payments (ie. interest/dividend payments to other countries for their investments in the US). This is basically what is meant when they say that the US is borrowing from the rest of the world. And obviously it isn't sustainable.
The trade deficit shows that the US is importing more than it exports, but the current account deficit shows that the US is spending more than it earns. The problem with a growing current account deficit is that an increasing proportion of US income (GDP) is required for factor payments (ie. interest/dividend payments to other countries for their investments in the US). This is basically what is meant when they say that the US is borrowing from the rest of the world. And obviously it isn't sustainable.